=head1 NAME
-perldelta - what is new for perl v5.21.8
+[ this is a template for a new perldelta file. Any text flagged as XXX needs
+to be processed before release. ]
+
+perldelta - what is new for perl v5.21.10
=head1 DESCRIPTION
-This document describes differences between the 5.21.7 release and the 5.21.8
+This document describes differences between the 5.21.9 release and the 5.21.10
release.
-If you are upgrading from an earlier release such as 5.21.6, first read
-L<perl5217delta>, which describes differences between 5.21.6 and 5.21.7.
+If you are upgrading from an earlier release such as 5.21.8, first read
+L<perl5219delta>, which describes differences between 5.21.8 and 5.21.9.
=head1 Notice
-With this release we are now in the contentious changes portion of the code
-freeze as we prepare for the next stable release of Perl 5.
+XXX Any important notices here
=head1 Core Enhancements
-=head2 The warnings pragma now supports warnings outside of "all"
+XXX New core language features go here. Summarize user-visible core language
+enhancements. Particularly prominent performance optimisations could go
+here, but most should go in the L</Performance Enhancements> section.
-Ever since perl v5.6.0 we've had no way of adding new warnings without
-retroactively adding them to all existing programs that used C<-w>,
-C<-W> or C<use warnings>.
+[ List each enhancement as a =head2 entry ]
-This caused us to not add new useful warnings out of fear that they
-might unduly burden users who just wanted to upgrade perl and didn't
-want to deal with a bunch of warnings from their existing code.
+=head1 Security
-We now support a way to have our cake and eat it too, and can add new
-warnings to the core going forward through other top-level warning
-categories. See L<the warnings documentation|warnings/Top-level
-warning categories & associated confusion> for details.
+XXX Any security-related notices go here. In particular, any security
+vulnerabilities closed should be noted here rather than in the
+L</Selected Bug Fixes> section.
-=head2 Non-Capturing Regular Expression Flag
+[ List each security issue as a =head2 entry ]
-Regular expressions now support a C</n> flag that disables capturing
-and filling in C<$1>, C<$2>, etc... inside of groups:
+=head1 Incompatible Changes
- "hello" =~ /(hi|hello)/n; # $1 is not set
+XXX For a release on a stable branch, this section aspires to be:
-This is equivalent to putting C<?:> at the beginning of every capturing group.
+ There are no changes intentionally incompatible with 5.XXX.XXX
+ If any exist, they are bugs, and we request that you submit a
+ report. See L</Reporting Bugs> below.
-See L<perlre/"n"> for more information.
+[ List each incompatible change as a =head2 entry ]
-=head2 C<prototype> with no arguments
+=head1 Deprecations
-C<prototype()> with no arguments now infers C<$_>. [perl #123514]
+XXX Any deprecated features, syntax, modules etc. should be listed here.
-=head2 C<use re 'strict'>
+=head2 Module removals
-This applies stricter syntax rules to regular expression patterns
-compiled within its scope, which hopefully will alert you to typos and
-other unintentional behavior that backwards-compatibility issues prevent
-us from doing in normal regular expression compilations. Because the
-behavior of this is subject to change in future Perl releases as we gain
-experience, using this pragma will raise a category
-C<experimental:re_strict> warning.
-See L<'strict' in re|re/'strict' mode>.
+XXX Remove this section if inapplicable.
-=head2 New "const" subroutine attribute
+The following modules will be removed from the core distribution in a
+future release, and will at that time need to be installed from CPAN.
+Distributions on CPAN which require these modules will need to list them as
+prerequisites.
-The "const" attribute can be applied to an anonymous subroutine. It causes
-it to be executed immediately when it is cloned. Its value is captured and
-used to create a new constant subroutine that is returned. This feature is
-experimental. See L<perlsub/Constant Functions>.
+The core versions of these modules will now issue C<"deprecated">-category
+warnings to alert you to this fact. To silence these deprecation warnings,
+install the modules in question from CPAN.
-=head1 Incompatible Changes
+Note that these are (with rare exceptions) fine modules that you are encouraged
+to continue to use. Their disinclusion from core primarily hinges on their
+necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
+not usually on concerns over their design.
-=head2 sub signatures moved before attributes
+=over
-The experimental sub signatures feature, as introduced in 5.20, parsed
-signatures after attributes. In this release, the positioning has been
-moved such that signatures occur in exactly the same positioning a
-prototype would be found.
+=item XXX
+
+XXX Note that deprecated modules should be listed here even if they are listed
+as an updated module in the L</Modules and Pragmata> section.
+
+=back
+
+[ List each other deprecation as a =head2 entry ]
+
+=head1 Performance Enhancements
+
+XXX Changes which enhance performance without changing behaviour go here.
+There may well be none in a stable release.
+
+[ List each enhancement as a =item entry ]
+
+=over 4
+
+=item *
+
+The functions
+C<utf8::native_to_unicode()> and
+C<utf8::unicode_to_native()> (see L<utf8>)
+are now optimized out on ASCII platforms.
+There is now not even a minimal performance hit in writing code portable
+between ASCII and EBCDIC platforms.
+
+=back
=head1 Modules and Pragmata
=item *
-L<XXX> has been upgraded from version A.xx to B.yy.
+L<B> has been upgraded from version 1.56 to 1.57.
+
+=item *
+
+L<B::Deparse> has been upgraded from version 1.33 to 1.34.
+
+Deparse C<$#_> as that instead of as C<$#{_}>. [perl #123947]
+
+=item *
+
+L<CPAN> has been upgraded from version 2.05 to 2.10.
+
+=over 4
+
+=item *
+
+Add support for C<Cwd::getdcwd()> and introduce workaround for a misbehaviour
+seen on Strawberry Perl 5.20.1.
=item *
-L<attributes> has been upgraded from version 0.24 to 0.25.
+Fix C<chdir()> after building dependencies bug.
-Minor internal change only.
+=item *
+
+Introduce experimental support for plugins/hooks.
=item *
-L<B> has been upgraded from version 1.54 to 1.55.
+Integrate the App::Cpan sources.
-A bug where, after an ithread creation or psuedofork, special/immortal SVs in
-the child ithread/psuedoprocess did not have the correct class of
-C<B::SPECIAL>, has been fixed.
+=item *
-The C<id> and C<outid> PADLIST methods have been added.
+Do not check recursion on optional dependencies.
=item *
-L<B::Deparse> has been upgraded from version 1.31 to 1.32.
+Sanity check META.yml to contain a hash.
+L<[cpan #95271]|https://rt.cpan.org/Ticket/Display.html?id=95271>
-Deparsing C<BEGIN { undef &foo }> with the B<-w> switch enabled started to
-emit 'uninitialized' warnings in Perl 5.14. This has been fixed.
+=back
+
+=item *
-Deparsing calls to subs with a C<(;+)> prototype resulted in an infinite
-loop. The C<(;$>) C<(_)> and C<(;_)> prototypes were given the wrong
-precedence, causing C<foo($a<$b)> to be deparsed without the parentheses.
+L<CPAN::Meta> has been upgraded from version 2.143240 to 2.150001.
=item *
-L<File::Glob> has been upgraded from version 1.23 to 1.24.
+L<Data::Dumper> has been upgraded from version 2.157 to 2.158.
+
+=item *
-Avoid SvIV() expanding to call get_sv() three times in a few
-places. [perl #123606]
+L<DynaLoader> has been upgraded from version 1.31 to 1.32.
=item *
-L<Module::Metadata> has been upgraded from version 1.000025 to 1.000026.
+L<Encode> has been upgraded from version 2.70 to 2.72.
=item *
-L<Safe> has been upgraded from version 2.38 to 2.39.
+L<encoding> has been upgraded from version 2.13 to 2.14.
-C<reval> was not propagating void context properly.
+=item *
+
+L<Getopt::Long> has been upgraded from version 2.43 to 2.45.
=item *
-L<SDBM_File> has been upgraded from version 1.12 to 1.13.
+L<locale> has been upgraded from version 1.05 to 1.06.
-Simplified the build process. [perl #123413]
+=item *
+
+L<Locale::Codes> has been upgraded from version 3.33 to 3.34.
+
+=item *
+
+L<Module::CoreList> has been reverted from version 5.20150220 to 5.20150320.
+
+=item *
+
+L<Pod::Functions> has been upgraded from version 1.08 to 1.09.
+
+=item *
+
+L<POSIX> has been upgraded from version 1.51 to 1.52.
+
+=item *
+
+L<re> has been upgraded from version 0.31 to 0.32.
+
+=item *
+
+L<Test::Simple> has been reverted from version 1.301001_098 to 1.001014.
+
+=item *
+
+L<Text::Balanced> has been upgraded from version 2.02 to 2.03.
+
+No changes to installed files other than the version bump.
+
+=item *
+
+L<Text::ParseWords> has been upgraded from version 3.29 to 3.30.
+
+=item *
+
+L<threads> has been upgraded from version 1.96_001 to 2.01.
+
+=item *
+
+L<utf8> has been upgraded from version 1.14 to 1.15.
+
+=item *
+
+L<XS::APItest> has been upgraded from version 0.70 to 0.71.
=back
=head1 Documentation
+XXX Changes to files in F<pod/> go here. Consider grouping entries by
+file and be sure to link to the appropriate page, e.g. L<perlfunc>.
+
=head2 New Documentation
-=head3 L<perlunicook>
+XXX Changes which create B<new> files in F<pod/> go here.
-This document, by Tom Christiansen, provides examples of handling Unicode in
-Perl.
+=head3 L<XXX>
-=head1 Diagnostics
+XXX Description of the purpose of the new file here
-The following additions or changes have been made to diagnostic output,
-including warnings and fatal error messages. For the complete list of
-diagnostic messages, see L<perldiag>.
+=head2 Changes to Existing Documentation
-=head2 New Diagnostics
+XXX Changes which significantly change existing files in F<pod/> go here.
+However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
+section.
-=head3 New Errors
+=head3 L<perldata>
=over 4
=item *
-L<Bad symbol for scalar|perldiag/"Bad symbol for scalar">
+Documentation has been added regarding the special floating point values C<Inf>
+and C<NaN>.
+
+=back
-(P) An internal request asked to add a scalar entry to something that
-wasn't a symbol table entry.
+=head3 L<perlexperiment>
+
+=over 4
=item *
-L<:const is not permitted on named subroutines|perldiag/":const is not permitted on named subroutines">
+Removed note about C<\s> matching C<VT> now that it is no longer experimental.
-(F) The "const" attribute causes an anonymous subroutine to be run and
-its value captured at the time that it is cloned. Names subroutines are
-not cloned like this, so the attribute does not make sense on them.
+=item *
+
+Added note that C<use re 'strict'> has been introduced experimentally.
=back
-=head3 New Warnings
+=head3 L<perlpolicy>
=over 4
=item *
-L<:const is experimental|perldiag/":const is experimental">
+The documentation of what to expect to see in future maintenance releases has
+been updated. Essentially the same types of changes will be included as before
+but with fewer changes that don't affect the installation or execution of perl.
-(S experimental::const_attr) The "const" attribute is experimental.
-If you want to use the feature, disable the warning with C<no warnings
-'experimental::const_attr'>, but know that in doing so you are taking
-the risk that your code may break in a future Perl version.
+=back
-=item *
+=head1 Diagnostics
-L<Non-finite repeat count does nothing|perldiag/"Non-finite repeat count does nothing">
+The following additions or changes have been made to diagnostic output,
+including warnings and fatal error messages. For the complete list of
+diagnostic messages, see L<perldiag>.
-(W numeric) You tried to execute the
-L<C<x>|perlop/Multiplicative Operators> repetition operator C<Inf> (or
-C<-Inf>) or C<NaN> times, which doesn't make sense.
+XXX New or changed warnings emitted by the core's C<C> code go here. Also
+include any changes in L<perldiag> that reconcile it to the C<C> code.
-=item *
+=head2 New Diagnostics
-L<Useless use of attribute "const"|perldiag/Useless use of attribute "const">
+XXX Newly added diagnostic messages go under here, separated into New Errors
+and New Warnings
-(W misc) The "const" attribute has no effect except
-on anonymous closure prototypes. You applied it to
-a subroutine via L<attributes.pm|attributes>. This is only useful
-inside an attribute handler for an anonymous subroutine.
+=head3 New Errors
-=item *
+=over 4
-L<Unusual use of %s in void context|perldiag/"Unusual use of %s in void context">
+=item *
-(W void_unusual) Similar to the "Useless use of %s in void context"
-warning, but only turned on by the top-level "pedantic" warning
-category, used for e.g. C<grep> in void context, which may indicate a
-bug, but could also just be someone using C<grep> for its side-effects
-as a loop.
+L<Invalid quantifier in {,} in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/">
-Enabled as part of "extra" warnings, not in the "all" category. See
-L<warnings> for details
+(F) The pattern looks like a {min,max} quantifier, but the min or max could not
+be parsed as a valid number - either it has leading zeroes, or it represents
+too big a number to cope with. The S<<-- HERE> shows where in the regular
+expression the problem was discovered. See L<perlre>.
-=item *
+=back
-L<E<quot>use re 'strict'E<quot> is experimental|perldiag/"use re 'strict'" is experimental>
+=head3 New Warnings
-(S experimental::re_strict) The things that are different when a regular
-expression pattern is compiled under C<'strict'> are subject to change
-in future Perl releases in incompatible ways. This means that a pattern
-that compiles today may not in a future Perl release. This warning is
-to alert you to that risk.
+=over 4
=item *
-L<Wide character (U+%X) in %s|perldiag/"Wide character (U+%X) in %s">
-
-(W locale) While in a single-byte locale (I<i.e.>, a non-UTF-8
-one), a multi-byte character was encountered. Perl considers this
-character to be the specified Unicode code point. Combining non-UTF8
-locales and Unicode is dangerous. Almost certainly some characters
-will have two different representations. For example, in the ISO 8859-7
-(Greek) locale, the code point 0xC3 represents a Capital Gamma. But so
-also does 0x393. This will make string comparisons unreliable.
-
-You likely need to figure out how this multi-byte character got mixed up
-with your single-byte locale (or perhaps you thought you had a UTF-8
-locale, but Perl disagrees).
+XXX L<message|perldiag/"message">
=back
=head2 Changes to Existing Diagnostics
+XXX Changes (i.e. rewording) of diagnostic messages go here
+
=over 4
=item *
-The message
-L<Locale '%s' may not work well.%s|perldiag/"Locale '%s' may not work well.%s">
-is no longer raised unless the problemtatic locale is actually used in
-the Perl program. Previously it was raised if it merely was the
-underlying locale. All Perl programs have an underlying locale at all
-times, but something like a C<S<use locale>> is needed for that locale
-to actually have some effect. This message will not be raised when
-the underlying locale is hidden.
+XXX Describe change here
=back
-=head1 Configuration and Compilation
+=head1 Utility Changes
+
+XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
+Most of these are built within the directory F<utils>.
+
+[ List utility changes as a =head2 entry for each utility and =item
+entries for each change
+Use L<XXX> with program names to get proper documentation linking. ]
+
+=head2 L<XXX>
=over 4
=item *
-pthreads and lcl will be linked by default if present. This allows XS modules
-that require threading to work on non-threaded perls. Note that you must still
-pass C<-Dusethreads> if you want a threaded perl.
+XXX
=back
-=head1 Testing
+=head1 Configuration and Compilation
+
+XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
+go here. Any other changes to the Perl build process should be listed here.
+However, any platform-specific changes should be listed in the
+L</Platform Support> section, instead.
+
+[ List changes as a =item entry ].
=over 4
=item *
-A new test script, F<bigmem/subst.t>, has been added to test memory usage of
-subst on very large strings.
+XXX
-=item *
+=back
+
+=head1 Testing
-A new test script, F<op/anonconst.t>, has been added to test experimental
-:const subroutines.
+XXX Any significant changes to the testing of a freshly built perl should be
+listed here. Changes which create B<new> files in F<t/> go here as do any
+large changes to the testing harness (e.g. when parallel testing was added).
+Changes to existing files in F<t/> aren't worth summarizing, although the bugs
+that they represent may be covered elsewhere.
+
+[ List each test improvement as a =item entry ]
+
+=over 4
=item *
-A new test script, F<re/reg_nocapture.t>, has been added to test the new
-C</n> regexp flag.
+Tests for performance issues have been added in the file F<t/perf/taint.t>.
=back
=head1 Platform Support
-=head2 Platform-Specific Notes
+XXX Any changes to platform support should be listed in the sections below.
-=over 4
+[ Within the sections, list each platform as a =item entry with specific
+changes as paragraphs below it. ]
-=item Win32
+=head2 New Platforms
+
+XXX List any platforms that this version of perl compiles on, that previous
+versions did not. These will either be enabled by new files in the F<hints/>
+directories, or new subdirectories and F<README> files at the top level of the
+source tree.
=over 4
-=item *
+=item XXX-some-platform
-Previously, on Visual C++ for Win64 built Perls only, when compiling every Perl
-XS module (including CPAN ones) and Perl aware .c file with a 64 bit Visual C++,
-would uncondtionally have around a dozen warnings from hv_func.h. These
-warnings have been silenced. GCC all bitness and Visual C++ for Win32 were
-not affected.
+XXX
-=item *
+=back
-Support for building without PerlIO has been removed from the Windows
-makefiles. Non-PerlIO builds were all but deprecated in Perl 5.18.0 and are
-already not supported by F<Configure> on POSIX systems.
+=head2 Discontinued Platforms
-=item *
+XXX List any platforms that this version of perl no longer compiles on.
-Between 2 and 6 ms and 7 I/O calls have been saved per attempt to open a perl
-module for each path in C<@INC>.
+=over 4
-=back
+=item XXX-some-platform
+
+XXX
=back
-=head1 Internal Changes
+=head2 Platform-Specific Notes
-=over 4
+XXX List any changes for specific platforms. This could include configuration
+and compilation changes or changes in portability/compatibility. However,
+changes within modules for platforms should generally be listed in the
+L</Modules and Pragmata> section.
-=item *
+=over 4
-Added Perl_sv_get_backrefs() to determine if an SV is a weak-referent.
+=item XXX-some-platform
-Function either returns an SV * of type AV, which contains the set of
-weakreferences which reference the passed in SV, or a simple RV * which
-is the only weakref to this item.
+XXX
=back
-=head1 Selected Bug Fixes
+=head1 Internal Changes
-=over 4
+XXX Changes which affect the interface available to C<XS> code go here. Other
+significant internal changes for future core maintainers should be noted as
+well.
-=item *
+[ List each change as a =item entry ]
-A bug in regular expression patterns that could lead to segfaults and
-other crashes has been fixed. This occurred only in patterns compiled
-with C<"/i">, while taking into account the current POSIX locale (this usually
-means they have to be compiled within the scope of C<S<"use locale">>),
-and there must be a string of at least 128 consecutive bytes to match.
-[perl #123539]
+=over 4
=item *
-C<s///> now works on very long strings instead of dying with 'Substitution
-loop'. [perl #103260] [perl #123071]
-
-=item *
+XXX
-C<gmtime> no longer crashes with not-a-number values. [perl #123495]
+=back
-=item *
+=head1 Selected Bug Fixes
-C<\()> (reference to an empty list) and C<y///> with lexical $_ in scope
-could do a bad write past the end of the stack. They have been fixed
-to extend the stack first.
+XXX Important bug fixes in the core language are summarized here. Bug fixes in
+files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
-=item *
+[ List each fix as a =item entry ]
-C<prototype()> with no arguments used to read the previous item on the
-stack, so C<print "foo", prototype()> would print foo's prototype. It has
-been fixed to infer $_ instead. [perl #123514]
+=over 4
=item *
-Some cases of lexical state subs inside predeclared subs could crash but no
-longer do.
+Repeated global pattern matches in scalar context on large tainted
+strings were exponentially slow depending on the current match
+position in the string. [perl #123202]
-=item *
+=back
-Some cases of nested lexical state subs inside anonymous subs could cause
-'Bizarre copy' errors or possibly even crash.
+=head1 Known Problems
-=item *
+XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
+tests that had to be C<TODO>ed for the release would be noted here. Unfixed
+platform specific bugs also go here.
+
+[ List each fix as a =item entry ]
-When trying to emit warnings, perl's default debugger (F<perl5db.pl>) was
-sometimes giving 'Undefined subroutine &DB::db_warn called' instead. This
-bug, which started to occur in Perl 5.18, has been fixed. [perl #123553]
+=over 4
=item *
-Certain syntax errors in substitutions, such as C<< s/${<>{})// >>, would
-crash, and had done so since Perl 5.10. (In some cases the crash did not
-start happening till 5.16.) The crash has, of course, been fixed.
-[perl #123542]
+XXX
-=item *
+=back
+
+=head1 Errata From Previous Releases
-A repeat expression like C<33 x ~3> could cause a large buffer
-overflow since the new output buffer size was not correctly handled by
-SvGROW(). An expression like this now properly produces a memory wrap
-panic. [perl 123554]
+=over 4
=item *
-C<< formline("@...", "a"); >> would crash. The C<FF_CHECKNL> case in
-pp_formline() didn't set the pointer used to mark the chop position,
-which led to the C<FF_MORE> case crashing with a segmentation fault.
-This has been fixed. [perl #123538]
+XXX Add anything here that we forgot to add, or were mistaken about, in
+the perldelta of a previous release.
=back
+=head1 Obituary
+
+XXX If any significant core contributor has died, we've added a short obituary
+here.
+
=head1 Acknowledgements
XXX Generate this with:
- perl Porting/acknowledgements.pl v5.21.7..HEAD
+ perl Porting/acknowledgements.pl v5.21.9..HEAD
=head1 Reporting Bugs
https://perl5.git.perl.org / perl5.git / blobdiff